1. Field of the Invention
The present invention relates to a blood loss detection device and method for a hemodialysis system.
2. Prior Art
Hemodialysis is a known medical procedure through which a person's blood is cleansed of toxins. Hemodialysis is often prescribed when the kidneys no longer function properly for any of a number of reasons. Hemodialysis is typically performed at a hospital or dialysis center although there is interest in and a trend toward home use. In a dialysis treatment, the patient is connected to a hemodialysis machine via two tubes. The first tube is a blood intake tube and is responsible for removing blood from the patient and transferring it to the machine. When the blood enters the machine, it is cleaned via semi-permeable filters and then is pumped back to the patient through a blood return tubing. Before hemodialysis can be done, a doctor must make an entrance, often called an “access”, into the patient's blood vessels. This is sometimes done by minor surgery in the leg, arm or neck. The best access for many patients is called a “fistula”. Minor surgery may be performed to join an artery to a vein under the skin to make a larger vessel.
The dialysis process can take several hours for each procedure and may be done more than once per week depending on the condition. Even if done in the supervision of medical professionals, a patient cannot be monitored every minute. Additionally, a blanket or blankets will often be placed on the patient and the patient may attempt to nap or sleep during the procedure.
There have been reports of the return line becoming accidentally dislodged or pulled from the access site in the patient. If the dialysis machine and its accompanying pump continue to operate, blood will be drawn from the patient but will not properly be returned to the patient. If this condition continues, the patient can suffer loss of blood and even death. While the hemodialysis machines have existing pressure sensing devices, they may not sense the condition if the blood continues to pump. Additionally, if the patient is sleeping or if medical personnel are not constantly observing the entire procedure, blood loss may occur until it is discovered.
Several prior attempts have been made relating to various leak detection systems. For example, Van Antwerp et al. (U.S. Pat. No. 6,752,785) shows a wide variety of leak detection devices including devices as shown in FIGS. 10(a), 10(b) and 10(c). Each of these devices must be applied to the body of a user before a needle is inserted since each includes an enclosed circular opening. The Van Antwerp devices can not be installed once the return line is attached to the patient. If the Van Antwerp device was placed on the patient first, it would involve breaking the sterile field which is created and normally desirable on the skin of the patient before insertion of the needle. If the Van Antwerp device were to be placed prior to inserting the needle into the patient, the sterile field of the access site would be compromised, possibly resulting in an infection of the patient's blood.
Accordingly, it would be desirable to provide for protection of hemodialysis patients from exsanguination.
It would be desirable to provide a blood loss detection device and method which might be installed around a return line or needle connected to the patient.
It would also be desirable to provide a blood loss detection device and method which is simple and modular in design which could be easily placed or replaced without interruption of treatment.
It would further be desirable to provide a blood loss detection device and method which has both an alarm and a shut-down system which operates in conjunction with or separately from existing hemodialysis systems.
It would further be desirable to provide a blood loss detection device and method having a modular connection with a sensor system to confirm the modular connection.